Expansion valve



J as. I! 2 April 23, 1946. v. R. ANDREWS 9,

' EXPANSION VALVE Filed Dec. 19, 194i 2 Sheets-Sheet l --4& F07 I 45 65f 4f J5 mvsw'rom VERNON R. ANDRE W6 ATTORNEY.

Patented A r. 23.1946

EXPANSION VALVE Vernon R. Andrews, Milwaukee, Wis., assignor to Automatic Products Company,

Milwaukee,

Wis., a corporation of Wisconsin Application December 19, 1941, Serial 'No. 423,672'

11 Claims.

This invention relates in general to the control" of flow of fluids by condition -diilerentials and more particularly .to the fiow of liquids through an orifice.

An object of the invention is to provide, in an expansion valve. a means for controlling the flow of refrigerant therethrough when the suction pressure in an evaporator has reached a pre-de- 4 termined value.

Another object of the invention lies in the provisionof an expansion valve in which-the control of flow of refrigerant is maintained independent of the superheat''setting of the valve.

A still further object lies in the provision of a control device in which the fiow of refrigerant is maintained independent of load.

Still another object of the invention is to provide, in an expansion valve, a means for stopping the flow of refrigerant when the suction pressure on the system to which the valve is connected has reached a pre-determined value, independently of the orifice sizing of the valve.

A very important object is the provision of a liquid charged expansion valve which com- :iines superheat control and compressor protec- It is a main object of this invention to provide a liquid charged expansion valve which obviates theobiection of high pressures in the power element due to increased load, superheat increase etc., heretofore valves.

In the conventional expansion valve using a encountered in liquid chargedthe continued application of neat to the bulb will cause a continued rise in pressure within the bulb and consequently above the diaphragm.

With such inherent characteristics of the liquid charged valve high pressures may be obtained above the diaphragm which might be'objectionable for reasons hereinafter shown. With an excessive load on the evaporator a large amount of refrigerant will be passed thru the expansion valve orifice into the evaporator which will increase the back pressure in the evaporator coil. Refrigerant will be continually passed thru the orifice until the feeler bulb is cooled sufiiciently to decrease the pressure above the diaphragm to close the valve or until the back pressure in a the evaporator plus the force of the superheat 'spring .is large enough to overcome the pressure above the diaphragm. Thus with excessive loads A it is obvious that high back pressures will be encountered in the evaporator which will stall the compressor motor or otherwise overload the electric circuit beyond its normal operating capacity liquid charge the orifice of the valve is opened, 7

due to pressureincrease above the diaphragm of the expansion valve and in the feeler .bulb attached to the evaporator coil when the temperature of the evaporator coils has risen, to allowrefrigerant to enter the evaporator coil to reduce the temperature of saidv evaporator coil. When the refrigerant flows into the evaporator through the expansion valve oriflce controlled by the needle valve the suction pressure in the. evaporator is built up, which pressure also manifests itself beneath the diaphragm of the expansion valve tending to force the diaphragm upwardly so as to permit the needle valve to close the orifice.- This pressure beneath the diaphragm is a function of the evaporator pressure and has another force component, that of the superheat adjusting spring, acting parallel with it and in the same direction 'with respect to the diaphragm. In a liquid charged valve the pressure within the 'feeler bulb is a function of the heat applied to the bulb, and

and will result in a serious breakdown. This invention will control the back pressure independently of the pressure in the feeler bulb. 4

Other objects of the invention will appear, as the following preferred and modified embodiments of the device are explained in detail.

Figure'l is a view partly in vertical central section and partly in side elevation showing an expansion valve incorporating the' present invention.

Figure 2 is a central vertical sectional view" showing a modified form of the invention associated with a cut away portion-of an expansion valve; and

Figure 3 is a diagrammatic representation of the device of this invention incorporated into a refrigeration system.

Referring to the drawings the letter V exemplifies an expansion valve and the numeral Ill indicates generally the body portion of an expansion valve embodyingthe' device of this invention and having an outlet l2, an opening or inlet l4 threaded for the reception of a nipple l6 having an opening 16a communicating with the inlet H, said nipple being adapted to retain the strainer l8 therein. A boss portion 20, integral with the body portion,'and intermediate its inlet and outlet, is provided with a passage 22 which is sized to act as a-bearing surface for the push pin 24. The opening 4 in the valve body It communicates with the chamber 61a and the outlet I! to maintain the same pressures therein. The opening 26 of the body pora smaller central vertical opening 34 machined to form a smooth bearing surface for the needle valve 33, and lateral openings 32 extending radially from said large central opening. A valve seat element 38 is secured to the valve seat bushing 28 in any suitable manner such as soldering. The push pin 24 is reduced in diameter at its lower end to form a shoulder 40 which cooperates with the stop 42 to limit the upward movement of said stop with respect to push pin 2|. The stop 42 may be press fitted to the pin 24 or held securely thereto in any other manner and is designed to restrict the downward movement of the push pin by contact with the valve seat element 38.

' A head assembly 44 threadedly interengages the body portion at 46. A condition responsive means such as capillary tube 48 and feeler bulb 43 Is connected to the head assembly. This condition responsive means may respond to temperature conditions or pressure conditions as the case may be. The present embodiment of the invention utilizes temperature responsive means. The head assembly 44 includes the casings or outer walls 33 and 52 having horizontal outwardly extending annular flanges 54 and 53 respectively adapted to carry the outer diaphragm 58 between them a bushing 60 having a flange 82 cooperating with the rounded portion 84 of the casing 53 and held in sealed relationship therewith by silver soldering or the like at 38, an upper pad 33 and a lower pad 10, the pads forming an inner casing and being both securely fastened to the first or main diaphragm 58 by silver soldering, an inner pad 712 associated with the lower pad of the inner casing, and a second or inner diaphragm 13 carried by the upper and lower pads or walls of the inner casing. In the present embodiment the outer diaphragm 58 and inner diaphragm 16 is made of one piece of material forming two independently acting diaphragms. These diaphragms may be separate stampi'ngs. The upper and lower inner casing pads or walls 88 and luhave cut out portions 16 and 18 and flange portions 30 and 32 respectively which form walls for the chambers 33 and 88a. It should be noted that the stroke of the inner diaphragm 14 should be equai to or greater than the downward permissible stroke of V the outer diaphragm 53. The stroke of the inner diaphragm is restrictedby the arcuate surface 12a of the inner casing pad 38 and the down stroke of the outer diaphragm is limited by the Y downward movement of the inner casing pad 13 against the portion 52a of the casing 52.

The diaphragm 58 is securely attached to the flanges 54 and 53 at the periphery 34 and the diaphragms 13 and 38 are secured as by silver soldering to the upper and lower inner casing pads .at 86 to provide a pressure tight chamber 33. The

upper pad or wall 83 and inner diaphragm 33 form a chamber 38 which is to be charged to a pressure of a predetermined value. The charge which may be any anhydrous gas which will not condense at temperatures to which the valve is subjected is injected thru the tube 33 which is securely fitted into the hub portion 92 of the up.

per pad and in sealed relationship to the chamber 88. The outer diaphragm 53, upper pad 33, casing 50, capillary tube 43 and feeler bulb 43 comprise the chamber 131 for the liquid charge and is hermetically sealed. 4

The lower pad or wall 10 has acentral opening at cooperating with the down ardly extendi i can In is tapped to receive the valve seat bushing 28 which has a large central vertical opening 33,

annular flange 33 of the inner pad 12 which flange serves as a guide for said pad. The inner pad 12 has a horizontal annular flange 31 which co-acts with the lower pad 10 and is carried by said lower pad but is free to move vertically with respect to said pad. The annular flange 91 has transverse grooves 31a. which permit communication bedrawn up tightly against the gasket 23 to form a gas tight connection. The lower end of the housing 21 is counterbored at 3| and tapped for the interpolation of a plug 33 having an opening 31 therein through which the adjusting shaft 35 passes. The exterior of the lower portion of the housing 21 is threaded at 33 to engage the cap 4! which can be. removed to permit adjustment of the shaft 35. The adjusting shaft 35 engages the adjusting nut which is slidably connected thereto and is free to move axially of said adjusting shaft in order to vary the compressive force of the spring 43 on the flange portion 53 of the cup BI. A packing gland 61 is disposed'in the counterbore SI and circumscribes the shaft 35 to provide a gas tight chamber 49 which is of the same pressure as the incoming refrigerent.

. upper end of the needle valve 36 is limited by'the stop 32 which engagesthe'element 38 and in the drawings this stop and push pin are shown in their upward position with the needle valve 36 seating in the orifice at 55. In this position of the needle valve the ilow oi refrigerant to the evaporator is cut off.

Figure 2 illustrates a modified form of the invention in central vertical sectional view embodying only a portion of the expansion valve designated in Figure l with which it may be associated with similar parts being designated by the same numerals and in which the numeral I0 represents the body portion, an extension I 05 connects the body portion at 4B and engages the casing 52 at I36. In this form of the invention a diaphragm I01 is secured to the casings 52 and 30 in the same manner as hereinbeiore explained In the preferred embodiment. A shaft I03 is expanded at its lower end to form a bellows housing I I I which has its side walls II3 turned inwardly to provide a flange HE. A piston like element H1 is disposed within the walls H3 and is movable vertically therein. A bellows I2! is securely bonded to the housing III and the piston II1 to provide a hermetically sealed chamber I23. The housing III has an opening I23 therein for the reception of a charging tube I21 which communicates with the chamber I23 and is fixed to'the housing 'in any suitable manner. A bearing member MI is associated withtthe diaphragm I31 and coacts with the shaft I09. The piston I I 1 has a counterbored portion I33 which receives the push pin 24. The opening 4 in the valve body In communicates with outlet i2 and chamber It] so as to-main the same pressures therein.

,The pressure above the diaphragm ill, of-

course, will vary depending on the temperature of the feeler bulb 49 in the same manner as set out above. Since the piston H1 is loosely fitted into the side' walls H3 the space I38 between the bellows 1 2| and the side walls II! is the same pressure as the chamber I 35. The chamber I23 may be charged with an anhydrous gasto a pressure equal to the knock off pressure" (suction pressure desired to close the valve) plus the force of the adjusting spring.

Referring to Figure 3, the valve V of this invention is shown incorporated into a system comprising a heat transfer coil or evaporator I20, 8.

return line' I22, compressor I24, a motor I24 drivpressure or pressure at which it is desired the suction pressure of the evaporator shall reach before closing the valve, plus thepressure required to overcome the spring rate of inner diaphragm and spring 43, plus the force component of the spring 43 divided by the eilective area of the diaphragm- 14) of predetermined value determined from the knock ofi" pressuredesired. It might be that because of the size of the compressor, it is desirable that the suction pressure in the evaporator not exceed some selected pressure. The

pressure in the feeler bulb and above the diaphragm 58 rises due to an increase in the temperature of the evaporator coil, and deflects said diaphragm downwardly which in turn urges the push pin 24 against the needle valve 3| displacing it from its seatii. Opening the orifice 51 passes liquid refrigerant into the evaporator which causes'a pressure to build up in the evaporator and also lowers the temperature of the feeler bulb.-- That is, when anormal load is put on the system the feeler bulb warms up causing the valve to open'and admit refrigerant to the evaporator which removes heat from said evaporator coil and cools the feelerbulb which decreases the pressure in the chamber 61. But with an increase in suction pressure, which is a function of the refrigerant in the evaporator, a state of unbalance exists with the pressure on the lower side of thediaphragm 5&tending to close'the valve and the pressure above the diaphragm. tending to open the valve. Under conditions of normal load where the feeler bulb is not abnormally heated there will be a balancingand unbalancing be-. tween the suction pressure and the. pressure within the liquid charged feeler bulb and injuriously high suction pressures will not be encountered because the pressure in the feeler bulb will not rise to excessively high values whereby refrigerant will be continually passed into the evaporator and the suction pressure will continue to rise to close the valve until the evaporator pressurerequired to close the valve has become suiilciently high to break down preclude its starting.

However, there is no assurance that only normal loads will beput on a system, and this is why some protection, such as the present inven- 3 tion discloses. is necessar where liquid charged 'valves are used. a a

with a pre-determined vapor charge in chamber I! assume an excessive load is put on the evaporator coils to which the device of this invention is connected. This excessive load will cause a high pressure in the feeler bulb because of the temperature increase in the evaporator coils and the valve will be opened to its maximum flow. Under conditions such as this where large amounts of refrigerant are evaporated so .rapidly that the compressor is unable to pull the suction pressure down, and since the evaporator cell was.

in the first place abnormally warmed, the valve will "continue to remain open and pass more refrigerant which, of course, willcontinue to raise the suction pressure and this would keep 'up until the suction pressure became high enough to close the valve against the feeler bulb pressure if it were not for the "knock oil i'eaturev ofthis invention. But in the present invention it has been assumed for illustrative purposes that the chainber 88 has been charged to a predetermined value. Now, just as soon as the suction pressure which acts on the'inner diaphragm" plus the force of the spring 43 has reached this: value the inner diaphragm will be flexed upwardly and the spring 43 will move the needle valve up rdly o the orifice a corresponding amountiuntil the suction pressure has reached a chosen value to deflect the inner diaphragm the desired distanceto completely close the orifice. Regardless of the pres-' I sure above the outer diaphragm tending to force the needle valve open the inner diaphragm 14 will deflect upwardly whereby the push pin 24 is, moved upwardly by force of the spring 43 when the suction pressure has reached a selected value to close the valve.

There are other applicationsto which this invention may be adapted such as switching mech-' anisms, and control-devices requiring pressureor temperature differentials for operation.

While I have shown and described-a preferred embodiment of my invention, it will be readily appreciated that various changes and modifications of structures may be employed to meet different conditions in use and manufacture without, however, departing in any manner from the.

spirit of my invention claims.

Having described the invention, I claim: 1. In combination a valve body having an inlet as defined by the appended and an outlet. a valve seat between the inlet and the outlet, a valve cooperating with said valve seat, an adjusting mechanism adapted to control the valve and comprising a housing, an adjusting.

nut associated with the housing, a shaft, a spring abutting said adiustingnut at one of its ends, a cup associated with-said spring at its other end and cooperating with said valve to hold said valve against its seat, a head assemb y comprising a casing associated with the'valve'body, a second casing associated with the first casing, a vfirst diaphragm associated with said first and second casings, upper and lower pads associated v with the first diaphragm, a second diaphragm the compressor or associatedwith the upper and lower pads, an inner pad associated with said lower pad and said second diaphragm, a condition responsive means associated with said second casing, and

valve operatin means associated with said inner pad scribed comprising a valve body having an inlet and an outlet, a valve seat interposed between said An expansion valve of the character dewith said head assembly, one of said diaphragms being non-responsive with respect to the other said diaphragm at times of normal suction pres- .sure and responsive at times of abnormal suction pressure, and means associated with said head assembly foroperating said valve.

3. An expansion valve of the character described comprising a valve body having an inlet and an outlet, a valve seat interposed between said inlet and said outlet, means providing a chamber between said inlet and. said outlet, a valve disposed in said chamber, a head assembly associated with said valve body, a push pin associated with said assembly and operating said valve, temperature responsive means associated with said head assembly, said assembly comprising an outer diaphragm responsive to the pressures of said temperature responsive means and suction pressure, an inner diaphragm responsive to a predetermined pressure on one side andsuction ressure on its other side, said inner diaphragm collapsing when the suction pressure attains a predetermined value whereby said push pin may move upwardly to permit said valve to close.

f1. An expansion valve of the character described comprising a valve body having an inlet and an outlet, avalve seat interposed between said inlet and said outlet, means providing a chamber between said inlet and said outlet, a valve disposed in said chamber, a head assembly associated with said valve body, a push pin associated with'said assembly and operating said valve, temperture responsive means associated with said head assembly, said head assembly comprising a' first diaphragm, a second diaphragm, upper and lower pads associated with said first and said second diaphragms, the upward stroke of said second diaphragm being equal to or greater than the downward stroke of said first diaphragm to permit said push pin to move vertically to allow said valve to close when said first diaphragm has reached its maximum down stroke.

5. Anexpansion valve of the character described comprising a valve body having an inlet and an outlet, a valve seat interposed between said inlet and said outlet, a valve cooperating with said valve ,seatto control the flow of a refrigerant therethrough, a push pin associated with said valve, a casing associated with said valve body, a second casing associated with the said first casing, a condition responsive means associated with said second casing, a diaphragm interposed between said first and second casings, means associated with said diaphragm to permit said push pin to move upwardly regardless of the force actand an outlet, a valve seat interposed between.

said inlet and said outlet, a valve cooperating with said valve seat to control the flow of a refrigerant therethrough, a push pin associated with said able refrigerant, a valve body having an inlet and an outlet, a valve controlling the flow of refrigerant irom the inlet to the outlet, adjustable means urging the valve toward closed position, a head assembly connected with the valve body and comprising a plurality of casings, a, diaphragm dividing the casings into a plurality of expansible chambers, one of the chambers being charged to a predetermined pressure, a second chamber being connected with and under pressure of the refrigerant in the outlet and means opening a port and connecting a third chamber with the outlet upon rise of the pressure therein above a predetermined value, means responsive to change in temperature of the refrigerant in the outlet and connected with a fourth chamber to vary the pressure therein, and a pin engaging the valve and the wall of one of the chambers for opening the valve dependent on the relations or the pres sures within the chambers.

8. In a valve controlling the fiow of a vaporizablerei'rigerant, a valve body having an inlet and an outlet, a valve controlling the flow of refrigerant from the inlet to the outlet, adjustable means urging the valve toward closed position, a head assembly connected withthe valve body and comprising an outer casing, an inner casing, a diaphragm supporting the casings in spaced relation to each other and dividing the casings into' a plurality of expansible chambers, one of the chambers being under a predetermined pressure, a second chamber being connected with and under pressure of the refrigerant in the outlet and means opening a port and connecting a third chamber with the outlet upon rise of the pressure therein above a predetermined value, means responsive to change in temperature of the refrigerant in the outlet and connected with a fourth chamber to vary the pressure therein, and a pin engaging the valve and the wall oi. one of the chambers for opening the valve dependent on the relations of the pressures within the chambers. v

9. In a valve controlling the flow of a vaporiz able refrigerant, a valve body having an inlet and an outlet, a valve controlling the flow, of refrigerant from the inlet to the outlet. adjust- I able means urging the valve towards closed position, a head assembly connected with the valve body and comprising an outer casing, an inner casing, a flexible diaphragm supporting the inner casing within the outer casing, the inner casing andthediaphragm dividing the outer casinginto a plurality of chambers, a flexible diaphragm dividing the inner easing into a plurality of chambers, one chamber in the outer casing being under pressure or the refrigerant in the outlet and one chamber in the inner casing being under'a predetermined pressure and means opening a port and connecting the second chamber in the inner casing with the outlet against thepressure in the first inner casing chamber upon rise of the outlet pressure above a predetermined value, means responsive to the temperature of the refrigerant in the outlet and connected with the second outer casing chamber to vary the pressure therein, and a pin engaging the valve and the inner casing for opening the valve dependent on the relations of the pressure. within the several chambers. a

10. In a valve controlling the flow of a vaporizable refrigerant, a valve body having an inlet and an outlet, a valve controlling the flow of refrigerant from the inlet to the outlet, adjustable means urging th valve toward closed position, a head assembly connected with the valve body and comprising an outer casing, an inner casing, a flexible diaphragm supporting the inner casing within the outer casing, the inner casing and the diaphragm dividing the outer casing into two chambers, one chamber in the outer casing being under pressure of the refrigerant in the outlet, a flexible diaphragm dividing the inner casing into two chambers, one of the inner casing chambers being permanently" closed and charged at a predetermined pressure and the other inner easing chamber having an opening therein and a pad substantially closing the opening in the other said inner casing chamber under the action of the inner casing diaphragm thereof until lifting of the pad upon rise of the outlet pressure above the pressure in the closed inner casing chamber, change in the temperature of refrigerant in the outlet and connected with the other outer casing chamber to vary the pressure therein, and a the relation of the presmeans responsive to 11v In a valve controlling the flow of a-vaporizable refrigerant, a valve body having an inlet and an outlet, a valve controlling the flow'of refrigerant from theinlet to the outlet, an adjustable springurging the valve toward closed position, a head assembly connected with the valve body and comprising an outer casing, an inner casing, a flexible diaphragm supporting the inner casing in spaced relation within the outer casing, the inner casing and the diaphragm dividing the outer casing into a plurality of chambers, one outer casing chamber being under pressure of refrigerant in the outlet, a flexible diaphragm dividing the inner casing into a plurality of chambers, one inner casing chamber being under a predetermined pressure only and the other inner casing chamber having an opening thereinto, and a pad substantially the opening into said other inner c chamdiapressure in the said other inner casing-chamber coacting with the spring to close the valve against thepressureintheoneinnercasingchamher and in the other outer casing chamber vnrmon 1e armimws. 

